Tube and base structure



. Aug. 21,; 1945. w. P, KRUGER 2,383,263

TUBE AND BASE STRUCTURE Filed Feb.c12.' 1944 I Patented Al1g 21, 1945 IIUNITED gSTATE S PATENT OFFICE I TUBE AND BASE STRUCTURE William P.Kruger, New York,` N. Y., assignor to Electrons, Inc., Newark, N. J., acorporation of Delaware Application February 12, 1944, SerialNo. 522,170

` 2 claims. (c1. 17e- 32) This invention relates to the mounting of aglass bulb in a supporting base, and particularly to such a combinationin an electronic tube.

The object of the invention is to provide a bond between the bulb andthe base which willbe permanently secure and unaffected by handling andby the variations in heating and cooling of the tube in service. In theaccompanying drawing illustrating the invention in connection with anelectron tube Fig. 1 is an elevational view with a part of the basebroken away; I Fig.I 2 is a view on enlarged scale of the bulb and baseinverted and prepared for assemblyb Fig. 3 is a similar view showing thebulb and Ibase bonded together and Figs. 4 and 5 are transversesectional views` taken onthe line 4-4 of Fig. 3, Fig. 5 illustrating onexaggerated scale the eect of temperature changes. I

In the specific example shown in the drawing, the glass bulb ID has anouter or upper cap terminal III and inner or lower terminal wires I2,

the'base end I3 of the tube being 'reduced in die ameter and providingthe slightly tapered or inclined annular surface I4 at the area ofattachment to the base I I5. In assembled positionthe wire terminalsextend into and are fastenedto the contact pins I6 of the base. I

The base I is hollow with inner-chamber walls `l'IIgenerally cylindricaland terminating in an` `annular edge 1I8 the bulb I0.

at the point of attachment to In the tube of this invention the bondbetween the base and bulb is provided by anumber of separated areas ofcement 2l).` I

`These separate masses of softcement are prefn Ierably applied withinthe base edge I8 as shown and enough in amount to fill in rbetween thebase wall and the bulb surface I4 (Fig. 3) when the base I5 (Fig. 2) islowered into place over the end of the bulb I0 (Fig.` 3).

` The parts are retained in this inverted position until the cement hashardened, for instance by setting under heat as with aBakelitecementtype No, BC-2360. This cement is a mixture of finely I groundmarble dust with phenol-formaldehyde thermo-setting plastic and with theaddition of expansion (generally higher) than that of the glass of thebulb and the cracking of the glass'` bulb in service is believed to beoften due to the stresses resulting from the greater contraction duringcooling of' the cement bond extending around the full or a large portionof the periphery of the bulb.

In the construction of this invention,I such contraction stresses areavoided and the parts are relatively free to expand and contract withoutthedevelopment of excessive stresses. In Fig. 4 the parts are shownexpanded by heating of the tube` and in Fig. 5 the parts have contractedupon cooling, the effects being intentionally exaggeratedin the figuresof the drawing. During this cooling any tendency of the base to contractI `more or less than the bulb may-'be in part relieved by` slightdistortions of the base I5, mainly between the areas of cementing asindicated in Fig. 5 for relatively greater contraction of the base. Atthe same time the contracting of the cement masses 20 imposessubstantially no stresses on the base or bulb leaving `the parts free 0fany interaction tending to crack the bulb or weaken the bond between theIbulb` and the base.

'I'his construction also permits partialresidual I setting of the cement2i? under the heating of the I tube in service where, as is sometimesthe case,

some shellac, the precise proportions not being critical. Preferably theheating is carried tothe point of permanent polymerization and settingof the cement so that subsequent heating of the and very firm bonds tothe base I the heating during assembly has not been carried toIcompletesetting or polymerization. :The tube of this invention thus has the bulband the base permanently secured together in a manner which unaffectedby variations in the heating and cooling of the tube during manufactureand in" service and maintains a rm bond under all conditons.,` I

I Iclaini: I I

1. A bulb and base comprising a glass bulb Ihaving an annular surfacefor attachment to a base, a base of material of different coefcient ofexpansion from the glass of said bulb and having a hollow formation witha deformable edge adapted for attachmentl to said annular surface ofsaid bulb, and a plurality of individual masses of cement between saidbulb and base spaced. to leave intermediate open uncemented spaces andbond-` ed to the bulb and bnase surfaces to form separated' anchoragesfirmly attaching said edge to said annular surfaces while maintainingrelatively extensive intermediate surfaces of said bulb and :baseunattached and freeto shiftrelatively without overstressing the bulbunder variations in heating and cooling of the Itube.

2.`A bulb and base structure as set forth in claim 1 in which the massesof cement are fully set and hardened in place between the bulb and ibaseso that further heating under service conditions does not cause anysubstantial further setting and hardening. t

I I WILLIAM P. KRUGER.

